I have been on several antidepressants and every time, without fail, there is a period of "getting used" to them about one week into it that is almost unbearable--terrible anxiety, crying for long periods of time, insomnia....generally, just feeling totally crazy and awful. This has lasted anywhere from one to two weeks. Each time I want to quit, and have on a few occasions, because I couldn't stand it. But usually, if I just hang in there, those awful feelings go away. Another thing that helps A LOT is if your doctor can give you like two weeks worth of a benzo (ativan or klonopin have worked for me) and this takes the edge off and helps with the anxiety and insomnia.